LacIe Big Disk Extream vs. Hard Dirve Extream

Guys, what is the difference between these two drives? I cannot figure this out. Both are 500G, both are tripple interface. The only difference I found so far is RAID 0. However, the one with RAID 0 is cheaper... I am lost. Please help, I need to get one of them.

http://www.lacie.com/caen/products/product.htm?pid=10511

http://www.lacie.com/caen/products/product.htm?pid=10279

Regards,
KG